Interchangeable balance staff for watches



1941- J. H. BECKMANN INTERCHANGEABLE BALANCE STAFF FOP. WATCHES FiledFeb. 15, 1940 INVENTOR 14cm! fihzukcmm gw-W ATTORNEY cm. H

Patented Nov. 18, 1941 UNITED STATES PATENT OFFICE INTERCHANGEABLEBALANCE STAFF FOR WATCHES Jacob Hazai Beckmann, New York, N. Y.Application February 15, 1940, Serial No. 319,005

1 Claim.

This invention relates to new and useful im provements in a balancestaff for watches.

Heretofore balance wheels of watches were constructed with staffs whichare a drive fit. and which were hard to remove when it was necessary torepair the movement of the watch. After the repair work was completedand it was again desired to place the balance wheel on the balancestaff, it was necessary to hammer upon the staff in order to fixedlyattach the wheel thereto. After the watch had been repaired a number oftimes the hammering pounded down and compressed portions of the wheelbody resulting in a loose fit between these parts which permitted thewheel to slide on the staff.

More specifically, this invention proposes the construction of a slidefit for the staff of balance wheels which may be repaired any number oftimes without destroying the operative value of these parts.

Still further the invention proposes the use of a staff having acylindrical support portion which may be engaged into the axial openingof a balance wheel and also having a head portion engaging against aportion of said wheel body, and staff elements extending axially fromthe opposite ends of said portions for rotatively supporting the staffwithin the watch body.

As another object of this invention it is proposed to construct a noveltype of spring hub cap which may be threadedly engaged on the staffelement on the opposite side to the head portion of said staff andclamping this cap against the wheel to fixedly engage the balance wheelon the staff body, so as not to interfere with the fittings andpositioning of the usual hair spring of the watch.

As another object of the invention it is proposed to construct thecylindrical support portion and the head portion of the staff ofseparate sections and applying a means thereto for holding the separatesections in different relative positions to compensate for thecompressed wall areas which will be formed on the balance wheel body asthe result of repairing.

Still further the invention proposes the use of opposed overhangingflanges formed on the separate sections of the cylindrical supportportion and the head portion which may have shims engaged therebetweento separate these sections and compensate for the compressed wall areas.

For further comprehension of the invention, and of the objects andadvantages thereof, reference will be had to the following descriptionand accompanying drawing, and to the appended claim in which the variousnovel features of the invention are more particularly set forth.

In the accompanying drawing forming a material part of this disclosure:

Fig. 1 is a plan view of a balance wheel having a staff, constructedaccording to this invention.

Fig. 2 is an enlarged sectional view taken on the line 2-4 of Fig. 1.

Fig. 3 is a cross section of the hub cap per se.

Fig. 4 is an enlarged detailed view of a portion of Fig. 2.

Fig. 5 is a view similar to Fig. 4 but illustrating a modification ofthe invention.

Fig. 6 is a plan view of Fig. 5.

Fig.7 is another view similar to Fig. 4 but illustrating a still furthermodification of the invention.

Fig. 8 is a view similar to Fig. 4 but illustrating another modificationof the invention,

Fig. 9 is a perspective view of the tool which is to be used forengaging the spring hub cap on the staff.

The balance staff for watches, according to this invention, comprises abalance wheel body l0 having an axial opening II for a staff l2. Thisstaff I! has a cylindrical support portion l2 engaging into the axialopening H and a head portion [2 engaging against a portion of said wheelbody on one end of said opening. Trunnion elements l2 extend axiallyfrom the opposite ends of the support portion l2 and the head portion l2A hub cap I3 is threadedly engaged on the trunnion element l2 which isopposite the head portion l2 and may be clamped against a portion ofsaid wheel body ID for releasably holding the wheel l0 fixed upon thestaff [2.

The balance wheel body l0 consists of a rim portion Ill having aplurality of openings Ill into which balance pins I4 are threadedlyengaged to make the wheel operate properly on the staff I2. Spokes Illradiate from the inside wall of the rim Ill and converge on a commoncenter which is provided with said axial opening II. The staff I2 isconstructed of steel, while the balance wheel is constructed of brasswhich is a softer material then steel. For this reason the cylindricalsupport portion I2 of the staff l2 engages into the axial opening I! tosupport the walls of this opening to prevent them from being pressed outof shape when the hub cap I3 is clamped thereon to fixedly attach thebalance Wheel Hi to the staff l2.

The hub cap l3 engages into an enlarged recessed portion ll of the axialopening II and has its bottom edge engaged against the shoulder portionsll formed by this enlarged recess for fixedly clamping the spokes lbetween the bottom edge of the hub cap l3 and the top edge of the headportion IZ This hub cap has a threaded opening I3 which cooperates withcomplementary threads l2 formed on the trunnion elements l2 for clampingthe balance wheel upon the staff. The flange l3 of hub cap I3 is furtherprovided with radial slots I3 into which a specially constructed tool I5may be engaged for turning the cap 13 on and off the threaded trunnionelement l2. This specially constructed tool l5 comprises a strip ofmaterial l5 having beveled portions l5 formed onone of its ends whichmay be engaged into the slots 13 formed in the hub cap l3. The hub. caphas a domeshaped portion and therefore the .end of .the strip ofmaterial l5 which is provided with the bev- II to compensate for thecompressed wall portions.

This adjustment may be formed by engaging shims l1 between the opposedoverhanging flanges l2 and l2 of the cylindrical support portion I2 andthe head portion l2" respectively. When these shims are engaged betweenthe opposed flanges it increases the space be tween these flangescausing the cylindrical support portion l2 to be slightly withdrawn fromI the axial opening II to keep it out of contact eled edge also has adome-shaped cutout iii.

intermediate of the edges of the strip of material which conforms withthe dome onthe hub cap permitting it to be engaged over the top of thiscap and into the slots 13' for turning the cap.

The tool If: is provided with a handle portion 15 in which a rotary stem[5' is held. This stem is formed with a head portion I5 at one end forrotating the flat portion 15 at the other end of stem iii. A hairspringI6 is adapted to have one of its ends securely attached in any desiredway to the hub cap 13 for fixedly attaching it to the staff I2. Thishair spring I8 is of a construction which is generally used inconnection with balance wheels of this type and neither spring nor itsmanner of attachment forms any part of this invention.

In Figs. 5 and 6, the flange 13 of the hub cap !3 is fully embedded intoa recess Ill formed at the mid-portion of spoke l0 by bending the spokedownwardly into a U-shape l0.

I3 is flush with the top surface H) of the spoke "1, so as to permit thehair spring 16 to be connected close to the spoke surface Ill".

According to the modification of the invention shown in Fig. '7 a meansis provided for holding In this form of the invention the top surface offlange wall areas and repair clamping action of the hub cap.

This means comprises a staff 12 having a cylindrical supportportion l2integrally formed therewith and adapted toengage into an axial openingll formed in the spokes l0 of a balance Wheel Hi. This cylindricalsupport portion has an outward extending flange li on its bottom edgewhich engages the inner face of a separate head portion l2" which isformed with an inwardly directed flange lZ which engages the.

outer face of the cylindrical support portion l2 and against the bottomface of-the spoke HI in the vicinity of the axial opening II. A hub cap13 is provided with a threaded opening I3 which may be threadedlyengaged upon the trunnion element l2 which is opposite the head portionl2" for clamping the balance wheel on the head portion l2".

Whenit is seen that a portion of the spokes I0 in the vicinity of theaxial opening I l is becoming compressed from the clamping action of thehub cap [3 permitting the adjacent faces of the hub cap and thecylindrical support portion to with the hub cap l3 to permit this hubcap to properly clamp the balance wheel l0 upon the head portion l2" ofthe staff 12'. In other respects this "form of the invention is the sameas that shown in the previous figures, and corresponding parts may berecognized by the same reference numerals.

Furthermore, a staff constructed in accordance with this lattermodification of the invention may be used in connection with a balancewheel l0, having spokes IB of any desired thickness. If the spokes areconstructed of relatively thick material, fewer shims I! will be neededto keep the cylindrical support portion l2 from contacting thefhub cap13. On the other hand, if the spokes I 0 are of thinner material, itwill be required that more shims ll be engaged between the flanges IZ?and I2, for withdrawing the greater portion of the cylindrical portionl2 from the axial opening I I, and so keep this cylindrical supportportion i2 from contacting the hub cap 13.

In Fig. 8, the hub cap 23 is made integral; with spoke 20 and staff 22is screwed into the threaded opening 23 of thejhub cap. The head portion22 of the staff is provided with radial slots 2| for screwing the staffinto the'thread-ed hub cap.

a It is to be understood that this-device may be made in various sizesto accommodate different sizes of watches, also that the arrangement maybe fitted on present old watches or on any new manufactured watch.

While I have illustrated and described the preferred embodiments of myinvention, it is to be understood that I do not limit myself to theme--cise constructions herein disclosed andthe right is reserved to allchanges and modifications coming' within the scope of the invention asdefined in the appended claim. I I

Having thus described my invention,wh'at I claim as new, and desire "tosecure by United States Letters'Patent 'is: v

In awatch balance staff having a balance wheel body with an axialopening therethrough, a staff extending through said opening, said staffhaving an outwardly extendingflange on one side of said wheel body, ahub cap on the other side of said wheel body engaging said other side ofsaid body, 'a-sleeve member encircling said outwardly extending flangeand having an inwardly extending flange engaged between said outwardlydirected flange and said one side of said wheel body, and shims mountedbetween said flanges and within said sleeve member.

' JACOB HAZAI BECKMANN.

